I checked the Activity Monitor on OS X to see if it's the same and if I should do something. It's quite surprising:

    bird	         11,38 GB   119,8 MB		
    kernel_task	          8,82 GB    23,0 MB
    launchd	          8,46 GB    77,7 MB	
    revisiond	          8,35 GB   105,8 MB	
    Tweetbot	          3,01 GB    50,2 MB	
    Safari	        879,6 MB     10,0 MB	
    mds_stores          726,2 MB    570,1 MB		
    systemstatsd        695,0 MB    775,0 MB
    nsurlstorag         685,3 MB      9,5 MB	
    Google Chrom        681,4 MB    303,5 MB		
    iTerm2	        653,7 MB      1,6 GB	
    cfprefsd	        509,1 MB     45,8 MB	
    Papers 3.4.7        465,9 MB    169,8 MB
    cloudd	        441,3 MB      9,7 MB
    ruby	        224,6 MB      1,7 MB	
    coreduetd	        217,5 MB		
    Reeder	        207,2 MB     28,5 MB 
    apsd	         65,7 MB     11	MB    
    Safari	         55,3 MB     12,6 MB	

I've long gotten used to "bird" doing it's thing (something with the cloud I guess). But how can a twitter client write 3GB (while I'm not even actually using it?)